1. Field of the Invention
The present invention relates to an information processing apparatus capable of autonomously controlling the supply of power within the apparatus and a program for causing a computer to execute a power control method.
2. Description of the Related Art
Recently, in the field of computer system technology, power control technology is being developed that reduces power consumption when an apparatus is on standby by instantly restarting the power supply when the necessity to perform processing arises upon an input operation or the like being carried out with respect to the apparatus when the power supply within the apparatus had been stopped when processing was not being performed.
For example, technology is known that, for a portable device such as a PDA (Personal Digital Assistant), attempts to reduce power consumption during standby by causing the CPU to operate at a low frequency and automatically shift to a low power consumption mode that cuts the power supply to peripheral circuits when an operation is not performed for a certain period, and then return to a normal state to perform processing when an operation is performed.
Further, ordinary PCs (personal computers) are equipped with a function such as a suspend mode or standby mode, and these functions are effective in reducing unnecessary power consumption when a device is not being used for a long period, particularly in a device such as a notebook PC that is driven by a battery.
In a suspend mode or a standby mode, in many cases the CPU and a control part that is subordinate to the CPU alternately enter a standby state or an operating state. At that time, the CPU sends a control instruction to the subordinate control part and enters a standby state. The control part operates in accordance with the instruction and also writes the operation result in a register or the like after the operation is completed and then stops. Upon returning to an operating state from the standby state, the CPU determines the result of the operation from the contents written in the register or the like and then moves to the next control.
In this connection, technology relating to power control such as a suspend mode or a standby mode is disclosed in JP-A-9-114557.